I made this device to demonstrate how electricity and magnetism interact with each other in a visual way. The basic concept was to create a large and short lived pulse of current that passes through a coil. The huge current flowing in a circular motion produces a strong magnetic field very briefly. This field passes through a conductive ring. This rise and collapse of the magnetic field induces eddy currents in the conductive ring. These eddy currents produce an opposing magnetic field which intern repels the initial magnetic field caused by the pulsed coil. Provided enough current passes through the initial coil and the conductive ring has a low electrical resistance it will fire straight up in the air. As magnetic field strength gets weaker the further away you are from it, it is important to dump a lot of energy in the shortest possible amount of time to have the largest projectile range.
When I demonstrated this to my peers and my lecturer at college it used a standard mains rated toggle switch to make the circuit. However, after 2 discharges the switch contacts had become welded together internally so I created open frame contactor who’s tip could be replaced easily. While it is possible to touch both contacts and receive a 400v shock, precautions were taken to reduce the likely hood of that happening.
The capacitor bank was made from 20 individual 100uF 400V electrolytic capacitors which were put in parallel with each other to hold more energy. The bank itself was then put in parallel with the capacitor on an external camera flash charging circuit. A disposable camera was not used as they are only rated for 1.5V which would mean approximately twice the charging time of the current setup at 3V.